喀斯特山区TRMM降水数据降尺度研究

获取高精度的卫星降水数据,为喀斯特区域旱涝灾害评估、水文预报等各研究领域提供数据基础。以热带降雨卫星(tropical rainfall measuring mission, TRMM)为数据源,采用多元线性回归法(ordinary least square, OLS)和地理加权回归法(geographically weighted regression, GWR),综合考虑高程、坡度、坡向、经纬度和归一化植被指数(normalized difference vegetation index, NDVI)等6个因子构建OLS和GWR降尺度模型进行年降尺度研究,并比较OLS和GWR两种降尺度模型在喀斯特山区的适用性。结果表明:1)TRMM数据与站点观测数据之间精度较好;2)降尺度后数据空间分辨率提升到1 km, GWR降尺度年降水量在多数年份比原始TRMM数据更接近实测值,高估现象得到改善;与OLS降尺度数据相比,其三项指标表现更好;3)单站点中,OLS降尺度数据在高程和NDVI突变区域易出现假性更优相关性。综合多指标评价,GWR降尺度数据在喀斯特山区总体精度更高。后续可通过划分植被区、岩溶区、增加环境因子、校正等使降水更贴合实测值。

滦河流域TRMM卫星降水数据适用性研究

利用滦河流域8个雨量站点2003—2019年实测降水资料,对TRMM卫星降水数据在滦河流域的适用性进行了评估。结果表明,TRMM降水量与实测降水量具有一致的年内分布规律和时空分布特征。在年、季、月时间尺度上,TRMM降水量具有较高的精度,普遍高于实测值,7月存在低估现象;夏秋季降水精度较高,冬季略差;7—10月精度较高,12月—次年2月精度较差。空间上,TRMM降水量精度随着海拔的降低而增加,在流域中上游TRMM降水量高估,沿海地区略微低估,乐亭站、秦皇岛站存在低估现象。

青海地区TRMM 3B43降水产品融合降尺度与时空特征分析

卫星遥感降水产品已广泛应用于估算降水,尤其是在地面观测站点稀少的地区。然而,这些卫星降水产品较低的空间分辨率,限制了其在局部地区的应用。因此,提出一种基于块到点克里金插值算法(ATPOK)与地理权重回归克里金残差校准算法(GWRK)组合的融合降尺度框架,对2000—2019年青海地区TRMM 3B43进行空间降尺度,并结合地面观测站点数据、归一化植被指数(NDVI)、数字高程模型(DEM)、坡度及坡向等辅助因子进行校准,最终得到1 km分辨率的降水产品。结果表明:(1)本研究所提出的融合降尺度框架能有效提高TRMM 3B43降水数据的降尺度精度,但并不能消除TRMM 3B43降水高估的情况。(2)与ATPOK算法相比,采用降尺度的TRMM降水数据和辅助因子的GWRK模型能更好地估算年、月降水量。(3)基于对TRMM 3B43和NDVI相关关系研究,发现NDVI对降水的响应存在0~2个月的延迟。(4)基于对降尺度降水产品时空变化分析,发现青海地区降水在月尺度上存在显著增长,其中干月年际变化率3.33%,湿月年际变化率1.79%。

A Planning Method for Operational Test of UAV Swarm Based on Mission Reliability

The unmanned aerial vehicle(UAV)swarm plays an increasingly important role in the modern battlefield,and the UAV swarm operational test is a vital means to validate the combat effectiveness of the UAV swarm.Due to the high cost and long duration of operational tests,it is essential to plan the test in advance.To solve the problem of planning UAV swarm operational test,this study considers the multi-stage feature of a UAV swarm mission,composed of launch,flight and combat stages,and proposes a method to find test plans that can maximize mission reliability.Therefore,a multi-stage mission reliability model for a UAV swarm is proposed to ensure successful implementation of the mission.A multi-objective integer optimization method that considers both mission reliability and cost is then formulated to obtain the optimal test plans.This study first constructs a mission reliability model for the UAV swarm in the combat stage.Then,the launch stage and flight stage are integrated to develop a complete PMS(Phased Mission Systems)reliability model.Finally,the Binary Decision Diagrams(BDD)and Multi Objective Quantum Particle Swarm Optimization(MOQPSO)methods are proposed to solve the model.The optimal plans considering both reliability and cost are obtained.The proposed model supports the planning of UAV swarm operational tests and represents a meaningful exploration of UAV swarm test planning.

Strategic Study on the Development of Space Science in China and Proposals for Future Missions

Since 2011,the Chinese Academy of Sciences(CAS)has implemented the Strategic Priority Program on Space Science(SPP).A series of scientific satellites have been developed and launched,such as Dark Matter Particle Explorer(DAMPE),Quantum Experiments at Space Scale(QUESS),Advanced Space-based Solar Observatory(ASO-S),Einstein Probe(EP),and significant scientific outcomes have been achieved.In order to plan the future space science missions in China,CAS has organized the Chinese space science community to conduct medium and long-term development strategy studies,and summarized the major scientific frontiers of space science as“One Black,Two Dark,Three Origins and Five Characterizations”.Five main scientific themes have been identified for China’s future breakthroughs,including the Extreme Universe,Space-Time Ripples,the Panoramic View of the Sun and Earth,the Habitable Planets,and Biological&Physical Science in Space.Space science satellite missions to be implemented before 2030 are proposed accordingly.

Comparison of the Minimum Bounding Rectangle and Minimum Circumscribed Ellipse of Rain Cells from TRMM

Based on the TRMM dataset, this paper compares the applicability of the improved MCE(minimum circumscribed ellipse), MBR(minimum bounding rectangle), and DIA(direct indexing area) methods for rain cell fitting. These three methods can reflect the geometric characteristics of clouds and apply geometric parameters to estimate the real dimensions of rain cells. The MCE method shows a major advantage in identifying the circumference of rain cells. The circumference of rain cells identified by MCE in most samples is smaller than that identified by DIA and MBR, and more similar to the observed rain cells. The area of rain cells identified by MBR is relatively robust. For rain cells composed of many pixels(N> 20), the overall performance is better than that of MCE, but the contribution of MBR to the best identification results,which have the shortest circumference and the smallest area, is less than that of MCE. The DIA method is best suited to small rain cells with a circumference of less than 100 km and an area of less than 120 km^(2), but the overall performance is mediocre. The MCE method tends to achieve the highest success at any angle, whereas there are fewer “best identification”results from DIA or MBR and more of the worst ones in the along-track direction and cross-track direction. Through this comprehensive comparison, we conclude that MCE can obtain the best fitting results with the shortest circumference and the smallest area on behalf of the high filling effect for all sizes of rain cells.

Life Origin in the Milky Way Galaxy: II. Scanning for Habitable Stellar Systems on Behalf of Future Space Missions

The possibility of the life origin in the stellar systems, located at a distance of ~200 pc from the solar system, was investigated. The stars, in the spectrums of which C (carbon), O (oxygen), N (nitrogen), and P (phosphorus) are found, are called DNA-stars. Based on stellar abundances a new method for searching for habitable exoplanets has been developed and a list of 48 DNA-stars in the solar neighborhood, on which life is possible, has been defined. The quota of DNA-stars is equal 1.3% of the total amount of Hypatia Stellar Catalog. Only three DNA-stars out of selected 48 stars belong to the spectral class as our Sun (G2V). The closest to the solar system is the DNA-star with the number HIP 15510, which belongs to the G8V class and is 6 pc away from the solar system. Nine DNA-stars, which have the highest chemical similarity with solar spectrum, were identified. It is identified that one of these nine stars, HIP 24681, has six planets.

Fast solution to the free return orbit's reachable domain of the manned lunar mission by deep neural network

It is important to calculate the reachable domain(RD)of the manned lunar mission to evaluate whether a lunar landing site could be reached by the spacecraft. In this paper, the RD of free return orbits is quickly evaluated and calculated via the classification and regression neural networks. An efficient databasegeneration method is developed for obtaining eight types of free return orbits and then the RD is defined by the orbit’s inclination and right ascension of ascending node(RAAN) at the perilune. A classify neural network and a regression network are trained respectively. The former is built for classifying the type of the RD, and the latter is built for calculating the inclination and RAAN of the RD. The simulation results show that two neural networks are well trained. The classification model has an accuracy of more than 99% and the mean square error of the regression model is less than 0.01°on the test set. Moreover, a serial strategy is proposed to combine the two surrogate models and a recognition tool is built to evaluate whether a lunar site could be reached. The proposed deep learning method shows the superiority in computation efficiency compared with the traditional double two-body model.

“Einstein Probe”Mission Holds New Promise in Time-domain Astronomy

Einstein Probe,an astronomical satellite designed for X-ray observation on astronomical events drastically evolving over time,was successfully sent into preset orbit by a Long March 2C rocket from China’s Xichang Satellite Launch Center located in Sichuan Province at 15:03 GMT+8 on January 9,2024.

基于GWR模型降尺度模拟蒙古高原地区TRMM降水数据

以多年月平均NDVI值高于0.1为阈值,对蒙古高原进行“植被区”与“非植被区”的子区域划分。在分析“植被区”植被对降水响应时滞性和“非植被区”陆地表面温度不同数据值与降水量相关性的基础上,子区域分别构建了TRMM3B43降水数据与海拔、坡度、坡向数据、归一化植被指数(NDVI)/陆地表面温度(LST)数据的地理加权回归(GWR)模型,得到区内2006-2015年每年5-10月1km空间分辨率的月降水量降尺度模拟数据,并利用区内141个气象站点数据对降尺度模拟数据进行精度验证。结果表明:(1)蒙古高原“植被区”植被对降水响应存在时滞性,约为一个月;“非植被区”多数月份白天与夜晚陆地表面温度差(LST_D_N)与降水量的相关性最显著。(2)降尺度模拟数据与气象站点数据具有较好的一致性,月尺度相关系数为0.83,各站点相关系数介于0.42~0.98。(3)在生长季、月平均尺度上,降尺度模拟数据具有较高精度,其中9月和10月数据精度优于TRMM 3B43数据。降尺度模拟数据整体精度较高,加之对原始数据在50°N以上未覆盖地区的填补以及空间分辨率的提高,可为区内水循环变化、农牧业生产、干旱监测等研究提供重要的数据支撑。

基于TRMM降尺度数据的渭河流域干旱时空演变特征与重心迁移规律研究

在气候变化背景下,渭河流域干旱频发,对其干旱时空分布特征及重心迁移规律进行探究具有重要意义。根据归一化差分植被指数、数字高程、坡度、坡向和经纬度等地理环境因子,构建多尺度地理加权回归模型,并对其进行降尺度处理,得到1 km分辨率的降水数据集,并利用气象站点实测数据进行降尺度数据的精度分析与校验。利用降尺度数据计算不同时间尺度标准化降水蒸散指数,借助重心模型和标准差椭圆,进一步分析渭河流域干旱演变特征,探索流域尺度干旱重心的迁移规律。结果表明:①降尺度处理后,降水数据精度得到一定改善,数据分辨率提升,空间分布更加细腻,细节特征表现更为准确;②不同时间尺度标准化降水蒸散指数在时间序列上波动性和周期性不同,可表征差异化的干旱情况,渭河流域干旱状况整体上呈随时间推移而逐步缓解的趋势,季尺度干旱在春、秋和冬季呈现缓和态势,且春旱和冬旱变化趋势较为明显;③不同时间尺度的干旱事件发生频率的空间分布不同,月尺度呈现局部区域上的高值,季尺度频率分布差异小、高值区少,年尺度频率跨度较大,高值区覆盖面积超过流域的50%;④近20年,干旱重心集中分布于流域中部,呈东北至西南的分布格局,重心迁移在空间上无规律,但整体上表现为东北向西南方向迁移的频率更高。研究得到一种高分辨率降水数据集,更加精细地表现了干旱演变特征和迁移规律,可为区域旱灾防控和水资源管理提供参考依据。

基于TRMM数据的江西省降水时空分布特征分析

对江西省地区降水的时空分布特征进行分析可以为江西水资源利用、灾害预测与农业发展等生态问题提供科学依据。本文使用地统计分析方法对江西省1998—2019年TRMM 3B43 V7降水数据进行时空特征分析。结果表明,(1)江西省降水在空间分布上呈现出东西两侧山区降水多,中部平原地区降水少的特征;(2)江西省年际降水波动大,研究时段内江西省年降水量整体呈现上升趋势;(3)江西省降水量在季节上分布不均匀,全年降水大部分集中于4—7月,且春夏两季的平均降雨量高于秋冬两季降雨量的2倍。

Mission reliability modeling and evaluation for reconfigurable unmanned weapon system-of-systems based on effective operation loop

The concept of unmanned weapon system-of-systems(UWSoS)involves a collection of various unmanned systems to achieve or accomplish a specific goal or mission.The mission reliability of UWSoS is represented by its ability to finish a required mission above the baselines of a given mission.However,issues with heterogeneity,cooperation between systems,and the emergence of UWSoS cannot be effectively solved by traditional system reliability methods.This study proposes an effective operation-loop-based mission reliability evaluation method for UWSoS by analyzing dynamic reconfiguration.First,we present a new connotation of an effective operation loop by considering the allocation of operational entities and physical resource constraints.Then,we propose an effective operationloop-based mission reliability model for a heterogeneous UWSoS according to the mission baseline.Moreover,a mission reliability evaluation algorithm is proposed under random external shocks and topology reconfiguration,revealing the evolution law of the effective operation loop and mission reliability.Finally,a typical 60-unmanned-aerial-vehicle-swarm is taken as an example to demonstrate the proposed models and methods.The mission reliability is achieved by considering external shocks,which can serve as a reference for evaluating and improving the effectiveness of UWSoS.

Precipitation scale effect of the TRMM satellite in Tianshan,China

High-resolution precipitation data is conducive to objectively describe the spatial-temporal variability of regional precipitation,and the study of downscaling techniques and spatial scale effects can provide technical and theoretical support to improve the spatial resolution and accuracy of satellite precipitation data.In this study,we used a machine learning algorithm combined with a regression algorithm RF-PLS(Random Forest-Partial Least Squares)to construct a downscaling model to obtain three types of high-resolution TRMM(Tropical Rainfall Measuring Mission)downscaled precipitation data for the years 2000-2017 at 250 m,500 m,and 1km.The scale effects with topographic and geomorphological features in the study area were analysed.Finally,we described the spatial and temporal variation of precipitation based on the optimal TRMM downscaled precipitation data.The results showed that:1)The linear relationships between the TRMM downscaled precipitation data obtained by each of the three downscaled models(PLS,RF,and RF-PLS)and the precipitation at the observation stations were improved compared to the linear relationships between the original TRMM data and the precipitation at the observation stations.The accuracy of the RF-PLS model was better than the other two models.2)Based on the RF-PLS model,the resolution of the TRMM data was increased to three different scales(250 m,500 m,and 1 km),considering the scale effects with topographic and geomorphological features.The precipitation simulation effect with a spatial resolution of 500 m was better than the other two scales.3)The annual precipitation was the highest in the areas with extremely high mountains,followed by the mediumhigh mountain,high mountain,medium mountain,medium-low mountain,plain,low mountain,and basin.

TRMM卫星降水数据在江苏省的适用性评价

利用江苏省内167个雨量站点2000—2013年的实测资料,多尺度检验和探讨TRMM卫星降水数据(TRMM 3B42日降水产品、TRMM 3B43月降水产品)在江苏省应用的可行性。在多年平均尺度上,TRMM降水数据和实测降水数据空间分布上均呈现从南向北递减,但TRMM降水值高于实测降水量。在日尺度上,通过降水频率、漏演和空演率、降水分级分别检验了TRMM 3B42降水数据与实测降水数据的吻合程度,连云港市和宿迁市漏演率和空演率均较低,在该两地可用TRMM反演数据较为准确地判别实际情况有无降水;TRMM 3B42数据对小雨测量的相对误差较大,对中雨、大雨、暴雨的相对误差较小。在月尺度上,通过相关性系数和绝对误差的检验,看出TRMM 3B43数据与地面实测数据一致性程度整体较高,其中在徐州、连云港北部相关性最高,在江苏南部、洪泽湖周边相关性略差。在年尺度上,比较了实测降水数据与TRMM降水数据的变差系数,两者呈现较一致的规律,江苏南部年降水量波动小,北部波动大。

Joint mission and route planning of unmanned air vehicles via a learning-based heuristic

Unmanned air vehicles(UAVs) have been regularly employed in modern wars to conduct different missions. Instead of addressing mission planning and route planning separately,this study investigates the issue of joint mission and route planning for a fleet of UAVs. The mission planning determines the configuration of weapons in UAVs and the weapons to attack targets, while the route planning determines the UAV’s visiting sequence for the targets. The problem is formulated as an integer linear programming model. Due to the inefficiency of CPLEX on large scale optimization problems, an effective learningbased heuristic, namely, population based adaptive large neighborhood search(P-ALNS), is proposed to solve the model. In P-ALNS, seven neighborhood structures are designed and adaptively utilized in terms of their historical performance. The effectiveness and superiority of the proposed model and algorithm are demonstrated on test instances of small, medium and large sizes. In particular, P-ALNS achieves comparable solutions or as good as those of CPLEX on small-size(20 targets)instances in much shorter time.

Research on agile space emergency launching mission planning simulation and verification method

Space emergency launching is to send a satellite into space by using a rapid responsive solid rocket in the bounded time to implement the emergency Earth observation mission.The key and difficult points mainly include the business process construction of launching mission planning,validation of the effectiveness of the launching scheme,etc.This paper pro-poses the agile space emergency launching mission planning simulation and verification method,which systematically con-structs the overall technical framework of space emergency launching mission planning with multi-field area,multi-platform and multi-task parallel under the constraint of resource schedul-ing for the first time.It supports flexible reconstruction of mis-sion planning processes such as launching target planning,tra-jectory planning,path planning,action planning and launching time analysis,and can realize on-demand assembly of operation links under different mission scenarios and different plan condi-tions,so as to quickly modify and generate launching schemes.It supports the fast solution of rocket trajectory data and the accurate analysis of multi-point salvo time window recheck and can realize the fast conflict resolution of launching missions in the dimensions of launching position and launching window sequence.It supports lightweight scenario design,modular flexi-ble simulation,based on launching style,launching platform,launching rules,etc.,can realize the independent mapping of mission planning results to two-dimensional and three-dimen-sional visual simulation models,so as to achieve a smooth con-nection between mission planning and simulation.

The Mission and Dilemma of College English Teachers in the New Era

The construction of world-class undergraduate education with Chinese characteristics is a major mission for all college English teachers in today’s era,and a considerable proportion of college English teachers are still in varying degrees of difficulties and bottlenecks.How to quickly achieve self-breakthrough and devote themselves to realizing the dream of serving the country and education is a higher requirement for college teachers at the national level.

习近平文化思想的价值、特质与内在逻辑

习近平文化思想坚持马克思主义的立场观点方法,坚守中华文化立场,是习近平新时代中国特色社会主义思想的文化篇,是中国共产党最新的文化思想成果。习近平文化思想明确了新时代文化建设的路线图和任务书,具有鲜明的实践导向性,为新形势下宣传思想文化工作提供了强大思想武器和科学行动指南。习近平文化思想具有丰富的价值意蕴,丰富和发展了马克思主义文化理论,指明和标注了新时代新的文化使命,也为实现中华民族伟大复兴提供行动指南并注入强大精神动力。习近平文化思想展现出了时代特质,坚守人民立场和政治底色、坚持宏微结合和体用贯通,并彰显了民族特性与世界眼光。习近平文化思想坚持和实现了历史性与现实性的统一,文化本体与文化形态的统一,合规律性与合目的性的统一,内在发展和外在保障的统一。把握习近平文化思想的内在逻辑,有利于深刻认识和理解习近平文化思想生成、存在和发展的内外动因。

习近平文化思想的科学性与实践性

党的十八大以来,习近平总书记高度重视党的宣传思想文化工作,主持召开一系列重要会议、发表一系列重要讲话、提出一系列新思想新观点新论断,形成了习近平文化思想。这一思想是一个内涵丰富、逻辑严密的理论体系,科学回答了关于党的宣传思想文化工作的一系列方向性、根本性、战略性的重大问题。这一思想具有深厚的实践基础,新时代十余年来党的宣传思想文化工作在习近平新时代中国特色社会主义思想的指引下,经过“正本清源”与“守正创新”接续努力,取得了历史性成就、发生了历史性变革,也积累了一系列宝贵经验。这一思想正是对党的宣传思想文化工作经验,尤其是新时代实践经验的科学总结。从新时代党的宣传思想文化工作重要经验及其背后逻辑来看,习近平文化思想的科学性和实践性得到进一步彰显和印证,我们党对宣传思想文化工作的规律性认识也进一步深化。